1. Field of the Invention
This invention relates to a paper feeding device to be incorporated in an image producing apparatus such as a thermal ink transfer recording system and adapted to convey a sheet material to an image forming part installed inside the image producing apparatus.
2. Description of the Prior Art
In an image producing apparatus such as a thermal ink transfer recording system, from a paper feeding cassette accommodating therein a pile of sheet materials or recording papers, the recording papers are played out one by one and conveyed in the direction of an image forming part installed inside the image producing apparatus. For the extraction of the recording papers from the paper feeding cassette, the practice of vertically reciprocating a vacuum pad relative to the pile of recording papers thereby generating a negative pressure and effecting the paper feeding by making use of this negative pressure as disclosed in Japanese Patent Laid-Open 1-256431, for example, has been conventionally employed if not invariably.
In the conventional technique of this nature, if the vacuum cup accidentally aspirates a plurality of sheet materials coherently at a stroke, the plurality of sheet materials in their coherent state are conveyed to the image forming part.
Japanese Patent Publication 56-18,492 discloses a paper feeding device. In this paper feeding device, a copying paper pulled up from the paper feeding cassette by the action of aspirating power is conveyed by the cooperation of a rotary roller and a pressing roller moved freely into and out of contact with the rotary roller. When a need arises to return a copying paper already extracted from the paper feeding cassette, this return of the copying paper cannot be attained by the paper feeding device under present discussion. This is because the thermal ink transfer recording system adapted to reproduce color images on a recording paper uses an ink film having inks of the three colors, e.g. yellow, magenta, and cyan, applied thereto and prints the color images sequentially superposed in the order of the colors mentioned above on the recording paper and, for the purpose of causing the color images of the second and third colors to be superposed and printed, requires the aforementioned return of the recording paper but encounters the misfortune that owing to the motion of this return, the recording paper inevitably interferes with a part serving the purpose of discharging a recording paper from the paper feeding cassette. Once this interference occurs, it entails misregistration of prints during the formation of color images and prevents images of high quality to be reproduced on the recording paper.
A primary object of this invention is to provide a paper feeding device which is designed to extract a recording sheet from a container accommodating a pile of such recording sheets and supply it to an image forming part and further adapted to preclude conveyance of a plurality of recording sheets in a coherent state.
Another object of this invention is to provide a paper feeding device which is provided with a sucker free to move vertically in both directions for extracting a recording sheet from the container and a first roller and a second roller jointly adapted to be paired so as to nip the recording sheet at the upper reach of the sucker and, therefore, is enabled to convey the recording sheet to an image forming part by means of the rollers.
Yet another object of this invention is to provide a small paper feeding device which is adapted to prevent the rollers and the recording sheet from interfering with each other when the recording sheet is returned to the position above the container in preparation for the superposition of a plurality of color images one after another on the recording sheet.
Still another object of this invention is to provide a paper feeding device which is so adapted that the outer peripheral surface of a roller contacts the leading end surface of a recording sheet being extracted from the container by the sucker and, when a plurality of recording sheets are coherently extracted, bends and separates asunder the coherent recording sheets and effects the return of the underlying recording sheets to the container.
A further object of this invention is to provide a paper feeding device which is so adapted that the roller for contact with the recording sheet being extracted from the container is rotated in the direction of advancing the recording sheet toward the container and causing a plurality of coherent recording sheets to be separated asunder
A further object of this invention is to provide a small paper feeding device which comprises a roller performing the function of separating asunder a plurality of coherent recording sheets in addition to the function of conveying the recording sheet to the image forming part.
A further object of this invention is to provide a paper feeding device which is so adapted that the cooperation of the sucker and the roller imparts a bend to the recording sheet raised to the position of the upper reach of the sucker and, even when a plurality of recording sheets are coherently raised by suction, effects the return of the underlying unnecessary recording sheets.
A further object of this invention is to provide a paper feeding device which is so adapted that the second roller is advanced into contact with the first roller after the elapse of a prescribed time following the arrival of the sucker dragging the recording sheet at the upper reach thereof and the cooperation of the two rollers causes the unnecessary recording sheets extracted by the sucker to fall infallibly into the container.
A further object of this invention is to provide a paper feeding device which is provided with a lever for causing the unnecessary recording sheets falling from the sucker to be returned to the container.
A further object of this invention is to provide a paper feeding device which is provided with a container possessing a step at the position opposite the sucker so that when the sucker contacts the recording sheet inside the container, the recording sheet is bent and the sucker is consequently allowed to contact the recording sheet without fail.
A further object of this invention is to provide a paper feeding device which is so adapted that the sucker and the first roller are jointly moved vertically in both directions.
In accordance with the present invention there is provided, a paper feeding device, comprising a sheet holding part for accommodating a stack of sheets an attracting member for attracting said sheets one at a time a first supporting member for supporting said attracting member so as to allow motion thereof to an attracting position and a feeding position, said attracting position representing a position at which said attracting member collides with the uppermost of the sheets accommodated in said sheet holding part and said feeding position representing a position which lies above said attracting position and, at the same time, issues said sheets to the next step a rotary member capable of moving between a first position at which said rotary member collides with the leading end of said sheet attracted by said attracting member and moved from said attracting position to said feeding position and a second position at which said rotary member collides with the lower surface of said sheet having been moved to said feeding position, and a second supporting member for rotatably supporting said rotary member.